Adherence to and Persistence With Statin Therapy in a Veteran Population

Background: A relative cardiovascular risk reduction of 25% to 35% has been reported in patients starting a statin for elevated cholesterol; yet many patients fail to consistently take these medications as directed. Objective: To evaluate factors affecting adherence and persistence with statin therapy. Methods: This retrospective study analyzed data from a Veterans Affairs database of facilities west of the Rocky Mountains. Patient demographics, co-morbidities, and prescription information was collected for individuals newly prescribed a statin between July 1, 2007, and December 31, 2012. Adherence was determined using the medication possession ratio (MPR). Persistence was defined as the time from initiation of therapy until a refill gap of 135 days or greater occurred. Results: Of 164 687 unique patients, overall adherence to statins a mean MPR of 0.843. Approximately 63% of patients were persistent with statin therapy 675 days after statin initiation. Patients prescribed pravastatin, atorvastatin, lovastatin, and rosuvastatin and those who took more than 1 different statin during the follow-up period had statistically significantly higher rates of adherence than those prescribed simvastatin. Older patients and those with a greater number of active prescriptions were found to be more adherent to statin medications. Patients with hypertension were more adherent to a statin, and those with diabetes mellitus and/or posttraumatic stress disorder (PTSD) were less adherent. Conclusion and Relevance: In veterans, overall statin adherence was excellent. Certain populations may benefit from interventions targeted at improving statin adherence, including younger veterans, those prescribed fewer medications, those taking simvastatin, and veterans with PTSD or diabetes mellitus.